This application is submitted in response to PAR-07-024 (Ancilla Studies to Major Ongoing NIDDK and NHLBI Clinical Research Studies). We are making application to continue our currently-funded project (R01DK075119O) and examine the extended cognitive effects of bariatric surgery in participants from the Longitudinal Assessment of Bariatric Surgery(:LABS) project. There is growing evidence that obesity is associated with adverse neurocognitive outcome. Recent studies demonstrate that elevated body mass index (BMI) is an independent risk factor for Alzheimer's disease, structural brain abnormalities, and cognitive dysfunction. Bariatric surgery is viewed as an effective intervention for morbid obesity, though its effects on cognition are largely unknown. Data from our currently-funded project indicate that uncomplicated bariatric surgery does not adversely impact cognitive function. Even more interesting, findings suggest that bariatric surgery actually improves cognitive function at short (12-weeks) in intermediate (12- and 24-months) follow-up, including gains in memory and executive function. No study has examined the cognitive effects of bariatric surgery at extended follow-up. Doing so will determine whether: 1) bariatric surgery protects against the accelerated cognitive decline found in obese individuals;and 2) cognitive function predicts weight re-gain in surgery patients. To examine this possibility, the proposed study will follow the 125 bariatric surgery patients and 75 obese matched controls enrolled in the currently-funded project. Bariatric surgery patients would complete assessments identical to the current project at 36-, 48-, and 60-months post-operatively and obese matched controls would do so at equivalent intervals. Each assessment quantifies cognitive function and factors known to contribution to cognitive function in morbid obesity, including, demographic characteristics, medical conditions, physical activity, and psychological symptoms. These methods would provide the first evidence for: 1) Proactive cognitive effects of bariatric surgery at extended follow up;2) Mechanism for these effects;and 3) Contribution of cognitive function to weight re-gain. PUBLIC HEALTH RELEVANCE: Obesity is independently associated with adverse neurocognitive outcome, including elevated risk for Alzheimer's disease and cognitive decline. Our data indicate that bariatric surgery improves cognitive function at short-term follow- up. The proposed study will determine whether bariatric surgery helps to protect against cognitive decline and whether cognitive function predicts weight re-gain.